Resin composition for capstock

ABSTRACT

A resin composition for capstock, comprising 100 to 30 parts by weight of an impact resistance modifier having a multilayer structure, and 0 to 70 parts by weight of a methyl methacrylate (co)polymer containing 50 to 100% by weight of methyl methacrylate and 50 to 0% by weight of a monomer which is copolymerizable therewith, wherein the total amount of the impact resistance modifier and the methyl methacrylate (co)polymer is 100 parts by weight, wherein the outer layer of said impact resistance modifier and/or said methyl methacrylate copolymer is copolymerized with 0.5 to 40% by weight of a reactive monomer based on the total amount of the impact resistance modifier and the methyl methacrylate (co)polymer as a polymer component, and wherein the homopolymer of said reactive monomer has an SP value of 9.8 (cal/cm 3 )/ 1/2  or more.

This application is 35 U.S.C. 371 national stage application ofPCT/US02/11849, filed Apr. 23,2002, which claims priority under 35U.S.C. 120 of provisional U.S. application Ser. No. 60/285,225, filedApr. 23, 2001.

FIELD OF THE INVENTION

The present invention relates to a resin composition for capstockcomprising an impact resistance modifier having a multilayer structure.Specifically, the present invention relates to a resin composition forcapstock having excellent impact resistance, weather resistance andprocessability and low gloss.

BACKGROUND OF THE INVENTION

Acrylic resins are well known to have excellent weather resistance. Bymaking use of this characteristic, they are used as a capstock for amaterial requiring weather resistance. For example, U.S. Pat. No.4,198,520 discloses improvement of weather resistance of the surface ofa molding made of a material inferior in weather resistance such as ABSresin, PVC resin or the like by using an acrylic resin as a capstock forthe surface. U.S. Pat. No. 5,318,737 and WO00/08098 disclosespreparation of an acrylic resin composition suited for use as a capstockexcellent in weather resistance and impact resistance by adding a rubbercomponent to an acrylic resin.

However, acrylic resins are fragile materials so that addition of alarge amount of rubber thereto is necessary for attaining impactresistance enough for satisfying the market demand, which leads to adeterioration in processability and surface hardness. A capstock wellbalanced between impact resistance and processability does not exist atpresent.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide, under the abovesituations, a capstock having excellent impact resistance, weatherresistance, surface hardness and processability which cannot so far beattained by the conventional acrylic resins.

The present inventors have carried out an extensive investigation. As aresult, it has been found that a capstock having excellent impactresistance, weather resistance, processability and surface hardness canbe obtained by copolymerizing a so-called polar monomer with, in anacrylic resin composition comprising an impact resistance modifier, theouter layer of the impact resistance modifier and/or the acryliccopolymer. Thus the present invention has been completed.

Specifically, the present invention relates to:

(1) A resin composition for capstock, comprising:

100 to 30 parts by weight of an impact resistance modifier having amultilayer structure, and

0 to 70 parts by weight of a methyl methacrylate (co)polymer containing50 to 100% by weight of methyl methacrylate and 50 to 0% by weight of amonomer which is copolymerizable therewith,

-   -   wherein the total amount of the impact resistance modifier and        the methyl methacrylate (co)polymer is 100 parts by weight,    -   wherein the outer layer of said impact resistance modifier        and/or said methyl methacrylate copolymer is copolymerized with        0.5 to 40% by weight of a reactive monomer based on the total        amount of the impact resistance modifier and the methyl        methacrylate (co)polymer as a polymer component, and    -   wherein the homopolymer of said reactive monomer has an SP value        of 9.8 (cal/cm³)^(1/2) or more.

-   (2) The resin composition according to (1), wherein the outer layer    of said impact resistance modifier and/or said methyl methacrylate    (co)polymer is copolymerized with 1 to 20% by weight of the reactive    monomer based on the total amount of the impact resistance modifier    and the methyl methacrylate (co)polymer.

(3) The resin composition according to (1), wherein the SP value of thehomopolymer of the reactive monomer is 10.8 (cal/cm³)^(1/2) or more.

-   (4) The resin composition according to (1), wherein the impact    resistance modifier and the methyl methacrylate (co)polymer are    contained in 80 to 40 parts by weight and 20 to 60 parts by weight,    and the total amount thereof is 100 parts by weight.-   (5) The resin composition according to (1), wherein the reactive    monomer is one or at least two of a monomer having a nitrile group,    an epoxy group, a glycidyl group, a hydroxyl group, a carboxylic    acid group, an aldehyde group, an amino group or an amide group.-   (6) The resin composition according to (1), wherein the impact    resistance modifier has a two-layer structure and is obtained by    polymerizing a monomer mixture containing a (meth)acrylic ester and    a copolymerizable monomer in the presence of a crosslinked acrylic    rubber.-   (7) The resin composition according to (1), wherein the impact    resistance modifier has a three-layer structure and is obtained by    polymerizing an alkyl acrylate, a copolymerizable monomer and a    crosslinking monomer in the presence of a polymer obtained by    polymerizing methyl methacrylate, a copolymerizable monomer and a    crosslinking monomer and then polymerizing a monomer mixture    containing a (meth)acrylic ester and a copolymerizable monomer in    the presence of the resulting two-layer polymer.-   (8) The resin composition according to (1), wherein a weight ratio    of the crosslinked rubber portion and the outer layer portion of    said impact resistance modifier according to (6) or (7) is 15/85 to    95/5.-   (9) The resin composition according to (1), wherein the capstock is    a capstock for a siding panel made of polyvinyl chloride.-   (10) A siding panel obtained by extrusion-molding the resin    composition according to (1) as a capstock and a polyvinyl chloride    resin as a substrate.-   (11) A siding panel obtained by extrusion-molding the resin    composition according to (1) as a capstock and a polyvinyl chloride    resin as a substrate using a multimanifold die.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the terms “part(s) by weight” and “% by weight” are simplyreferred to as “part(s)” and “%”, respectively, unless otherwiseindicated.

The methyl methacrylate (co)polymer can be obtained by copolymerizingmethyl methacrylate with a monomer which is copolymerizable therewith.Furthermore, it is obtained by copolymerizing 50 to 100% of methylmethacrylate with 0 to 50% of a monomer which is copolymerizabletherewith. Amounts of methyl methacrylate less than 50% are insufficientfor bringing about weather resistance improving effects of a capstockmolding so that they are not preferred. The amount of methylmethacrylate is preferably 60 to 98%, more preferably 75 to 90%.Examples of the monomer which is copolymerizable with methylmethacrylate include an aromatic vinyl, an acrylic ester, a methacrylicester other than methyl methacrylate, and the like.

The aromatic vinyl includes styrene, α-methylstyrene, chlorostyrene andthe like.

The acrylic ester includes ethyl acrylate, butyl acrylate, n-octylacrylate, 2-ethylhexyl acrylate.

The methacrylic ester includes ethyl methacrylate, butyl methacrylate,n-octyl methacrylate, 2-ethylhexyl methacrylate and the like.

They may be used either alone or in combination.

The copolymer of methyl methacrylate and a monomer which iscopolymerizable therewith is obtained by emulsion polymerization,suspension polymerization, bulk polymerization, solution polymerizationor the like. Among these, bulk polymerization is especially preferredbecause of a small content of impurities in the polymer.

The impact resistance modifier having a multilayer structure is amultilayer polymer obtained by one-stage or at least two-stagepolymerization of a vinyl monomer in the presence of rubbery polymerparticles. Examples of the rubbery polymer include acrylic rubber, dienerubber, silicone rubber and the like. Examples of the diene rubberinclude polybutadiene rubber, isoprene rubber, SBR, NBR and the like.Among these, acrylic rubber is preferred because they do not deterioratethe weather resistance of capstock obtained using it and the cost islow. Examples of the acrylic rubber include n-butyl acrylate rubber,n-octyl acrylate rubber, 2-ethylhexyl acrylate rubber and the like. Asthese rubbers, crosslinked rubber is usually employed. A compound usedfor the formation of the crosslinked structure is preferably allylmethacrylate, allyl acrylate, diallyl maleate, diallyl fumarate, diallylitaconate, monoallyl maleate, butadiene, divinyl benzene or the like.They are used either alone or in combination.

The impact resistance modifier having a multilayer structure is usuallyprepared by carrying out one-stage or at least two-stage polymerizationof 85 to 10% of a vinyl monomer in the presence of 15 to 90% ofcrosslinked rubber particles. The amount of the crosslinked rubberparticles is preferably 25 to 80%, more preferably 30 to 70%. Amountswithin this range are preferred from the viewpoints of processabilityand weather resistance. The crosslinked rubber particles may contain, asthe core, a rigid polymer in their inner layers. Examples of the vinylmonomer to be polymerized in the presence of rubbery polymer particlesinclude methyl methacrylate, ethyl methacrylate, methyl acrylate, ethylacrylate, butyl acrylate, styrene and the like. Any one of emulsionpolymerization, suspension polymerization, bulk polymerization andsolution polymerization can be employed for polymerization. Among these,emulsion polymerization is preferred because it facilitates control ofthe structure of the polymer.

The SP value of the homopolymer is calculated in accordance with theequation as described in The Society of Polymer Science, Japan, 2ndPolymer Material Forum, Gist of Lectures, p. 167 (1993). In this method,the calculation method of Small (P. A. Small; J. Appl. Chem., 3, 71(1953)) which is popularly known has been corrected so that the SP valueapproximates the found value.

Examples of the reactive monomer in which the homopolymer has an SPvalue of 9.8 (cal/cm³)^(1/2) or more of the present invention includeacrylonitriler methacrylonitrile, glycidyl methacrylate, 2-hydroxyethylacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, acrylicacid, methacrylic acid and the like. They may be used either alone or incombination. When the reactive monomer is used for the outer layer ofthe impact resistance modifier, it may be copolymerized uniformly withthe whole outer layer, or the outer layer may be divided into plurallayers, one to be copolymerized with the reactive monomer and the othernot to be copolymerized with the reactive monomer. Alternatively,copolymerization may be conducted while applying a concentrationgradient. The term “outer layer” as used herein means a layersurrounding the crosslinked rubber. When the above-described monomer isused for the methyl methacrylate (co)polymer, on the other hand, it maybe copolymerized with the whole (co)polymer or the (co)polymer may be amixture of a portion to be copolymerized with the monomer and anotherportion not to be copolymerized with the monomer.

The reactive monomer of the present invention is used for the methylmethacrylate (co)polymer and/or the outer layer of the impact resistancemodifier. Use of it for either one is preferred for attaining a lowgloss. The gloss is presumed to become low, because when it is used foreither one, compatibility between methyl methacrylate (co)polymer andthe outer layer of the impact resistance modifier lowers, therebylowering dispersibility of the impact resistance modifier in the methylmethacrylate copolymer, causing coagulation and inevitably making thesurface irregular. Excessive lowering in the compatibility is notpreferred because it induces deterioration in impact resistance.

When the content of the reactive monomer of the present invention isless than 0.5%, effects for improving impact resistance are notsufficient. Contents exceeding 40%, on the other hand, are not preferredfrom the viewpoint of weather resistance.

The SP value of the homopolymer is preferably 9.8 (cal/cm³)^(1/2) ormore, more preferably 10.8 (cal/cm³)^(1/2) or more. The amount of thereactive monomer is preferably 0.5 to 40%, more preferably 1 to 20%.

Various thermoplastic resins such as a polyvinyl chloride resin, an ABCresin and the like are employed as a substrate for capstock. Amongthese, the polyvinyl chloride resin is preferred from the viewpoint ofprocessability and weather resistance.

Siding sheets may be processed by laminating extrusion through apopularly used die such as feed block die or multimanifold die. Themultimanifold die is preferred because use of it permits production of agood sheet even if a capstock and a substrate which are different inviscosity are used in combination, and facilitates control of thicknessof the sheet.

There is no particular limitation imposed on a process for preparing theacrylic resin composition of the present invention. An acrylic resincomposition containing crosslinked rubber particles may be polymerizedin one operation, or an acrylic resin may be mixed with an impactresistance modifier. Additives such as an antioxidant, light stabilizer,lubricant, pigment and the like may be added as needed.

The present invention will hereinafter be described based on Examplesand Comparative Examples. However, the present invention is not limitedthereto.

EXAMPLE 1

Preparation of Methyl Methacrylate Copolymer:

In a reactor equipped with a stirrer were charged 200 parts of water and0.5 part of sodium dioctylsuccinate. After oxygen was removed from thespace and water in the reactor by nitrogen purging, the mixture washeated to 70° C. under stirring. To the reaction mixture were added0.004 part of sodium ethylenediaminetetraacetate, 0.002 part of ferroussulfate 7 hydrate, and 1 part of sodium formaldehyde sulfoxylate. Then,a mixture of 73 parts of methyl methacrylate, 15 parts of butylacrylate, 12 parts of acrylonitrile and 1 part of t-butyl hydroperoxidewas added continuously over 4 hours. Two hours after addition wasstarted, 0.5 part of sodium dioctylsuccinate was added in one operation.After completion of the continuous addition of the mixture, 0.1 part oft-butyl hydroperoxide and 0.1 part of sodium formaldehyde sulfoxylatewere added. Fifty minutes after completion of the addition, 0.1 part oft-butyl hydroperoxide was added. Ten minutes after that, 0.1 part ofsodium formaldehyde sulfoxylate was added. After completion of theaddition, the mixture was maintained at the same temperature for 1 hourto complete the polymerization. The methacrylic acid copolymer latexthus obtained was subjected to salting-out and coagulation, heattreatment and drying in a known manner, whereby a methyl methacrylatecopolymer was obtained as white powder. A monomer-to-polymer conversionratio was 96%.

Preparation of Two-layer Impact Resistance Modifier:

(a) Preparation of Rubbery Polymer

The mixture described below was charged in a glass reactor. Whilestirring in a nitrogen gas stream, the mixture was heated to 50° C. Amonomer mixture of 100 parts of n-butyl acrylate, 1 part of allylmethacrylate and 0.1 part of cumene hydroperoxide was added over 4hours. Simultaneously with the addition of the monomer mixture, a 5%aqueous solution of 2 parts of potassium stearate was added continuouslyover 4 hours. After the addition was completed, stirring was continuedfor 5 hours to complete the polymerization. A monomer-to-polymerconversion ratio was 97% and the polymer thus obtained was found to havean average particle size of 1300 Å.

Mixture: (parts) Deionized water 180 Potassium stearate 0.1 Formaldehydesodium sulfoxylate 0.2 Sodium ethylenediaminetetraacetate 0.01 Ferroussulfate heptahydrate 0.005(b) Preparation of Outer Layer

In a glass reactor were charged 70 parts (as a solid content) of thecrosslinked rubbery polymer latex obtained in (a), 0.08 part of sodiumformaldehyde sulfoxylate, 0.02 part of sodiumethylenediaminetetraacetate and 0.01 part of ferrous sulfateheptahydrate. At 50° C., the aqueous dispersion was stirred underheating in a nitrogen gas stream. Over one hour, 26 parts of methylmethacrylate and 4 parts of butyl acrylate, as monomer components forgraft polymerization, and, as a polymerization initiator, 0.05 part ofcumene hydroperoxide were added continuously. After completion of theaddition, 0.01 part of cumene hydroperoxide was added. Stirring wascontinued for 2 hours to complete the polymerization. Amonomer-to-polymer conversion ratio was 98%. The graft copolymer latexhaving a multilayer structure thus obtained was then subjected tosalting-out and coagulation, heat treatment and drying in a known mannerto thereby obtain a two-layer impact resistance modifier as whitepowder.

Preparation of Resin Composition:

To 45 parts of the resulting impact resistance modifier and 55 parts ofthe methyl methacrylate copolymer, 100 parts in total, were added 0.2part of an olefin lubricant (“ACPE-629A”, manufactured by Allied SignalInc.) and 1 part of an ultraviolet absorber (“TINUVIN-P”, manufacturedby Ciba Specialty Chemicals). The resulting mixture was kneaded in atwin-screw kneader, followed by pelletization. From the pellets, a sheetof 40 mil thick was formed by a T-die twin screw extruder.

The Gardner impact resistance (G.I., unit: inch·lb/mil) at 23° C. of thesample thus obtained was measured in accordance with ASTM D4226-93. Theresults are shown in Table 1.

EXAMPLE 2

In the same manner as in Example 1 except that the composition of themonomer mixture for a methyl methacrylate copolymer was changed to 73parts of methyl methacrylate, 15 parts of butyl acrylate and 12 parts ofglycidyl methacrylate and the composition of the monomer mixture for theouter layer of an impact resistance modifier was changed to 25 parts ofmethyl methacrylate and 5 parts of acrylonitrile, a methyl methacrylatecopolymer and an impact resistance modifier were prepared, followed bypelletization and formation of a sheet. The sheet was evaluated in thesame manner as in Example 1 and the results are shown in Table 1.

EXAMPLE 3

In the same manner as in Example 2 except that the composition of themonomer mixture for a methyl methacrylate copolymer was changed to 73parts of methyl methacrylate, 15 parts of butyl acrylate and 12 parts of2-hydroxyethyl acrylate, a methyl methacrylate copolymer and an impactresistance modifier were prepared, followed by pelletization andformation of a sheet.

The sheet was evaluated in the same manner as in Example 1 and theresults are shown in Table 1.

EXAMPLE 4

In the same manner as in Example 1, a methyl methacrylate copolymer wasprepared, while in the same manner as in Example 2, an impact resistancemodifier was prepared. They were kneaded and pelletized in the samemanner as in Example 1, followed by formation of a sheet.

The sheet was evaluated in the same manner as in Example 1 and theresults are shown in Table 1.

EXAMPLE 5

(a) Preparation of Rubbery Polymer

A rubbery polymer was prepared in the same manner as in Example 1.

(b) Polymerization of Outer Layer

In a glass reactor were charged 32 parts (as a solid content) of thecrosslinked rubbery polymer latex obtained in (a), 0.17 part of sodiumformaldehyde sulfoxylate, 0.044 part of sodiumethylenediaminetetraacetate and 0.022 part of ferrous sulfateheptahydrate. At 50° C., the aqueous dispersion was stirred underheating in a nitrogen gas stream. Then, as monomer components for graftpolymerization, 48 parts of methyl methacrylate, 10 parts of butylacrylate and 10 parts of acrylonitrile, and, as a polymerizationinitiator, 0.13 part of cumene hydroperoxide were added continuouslyover 2.5 hours. After completion of the addition, 0.17 part of cumenehydroperoxide and 0.2 part of sodium formaldehyde sulfoxylate wereadded. One hour thereafter, 0.17 part of cumene hydroperoxide and 0.2part of sodium formaldehyde sulfoxylate were added. Stirring wascontinued for 2 hours to complete the polymerization. Amonomer-to-polymer conversion ratio was 96%. The graft copolymer latexhaving a multilayer structure thus obtained was then subjected tosalting-out and coagulation, heat treatment and drying in a known mannerto thereby obtain a white powdery product.

Preparation of Resin Composition:

To 100 parts of the resulting impact resistance modifier were added 0.2part of an olefin lubricant (“ACPE-629A”, manufactured by Allied SignalInc.) and 1 part of an ultraviolet absorber (“TINUVIN-P”, manufacturedby Ciba Specialty Chemicals), while not adding a methyl methacrylatecopolymer. In the same manner as in Example 1, the resulting mixture waskneaded in a twin-screw kneader, followed by pelletization and formationof a sheet.

The sheet was evaluated in the same manner as in Example 1 and theresults are shown in Table 1.

COMPARATIVE EXAMPLE 1

In the same manner as in Example 1 except that the composition of themixture for a methyl methacrylate copolymer was changed to 85 parts ofmethyl methacrylate and 15 parts of butyl acrylate, a methylmethacrylate copolymer and an impact resistance modifier were prepared,followed by pelletization and formation of a sheet.

The sheet was evaluated in the same manner as in Example 1 and theresults are shown in Table 1.

TABLE 1 Comp. Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 1 Monomer AN AN & GMA AN& HA AN AN SP value (cal/cm³) 14.0 14.0 & 11.9 14.0 & 11.5 14.0 14.0Amount (%) 6.6 6.6 & 2.3 6.6 & 2.3 6.6 & 2.3 10.0 0 G. I. (inch ·lb/mil) 0.86 0.84 0.99 0.80 1.24 0.10 AN: Acrylonitrile GMA: Glycidylmethacrylate HA: 2-Hydroxyethyl acrylate

EXAMPLE 6

An impact resistance modifier similar to that used in Example 2 and as amethyl methacrylate copolymer, “ACRYLITE M-30-003” (trade name;manufactured by CYRO Industries) were used. In the same manner as inExample 1, 55 parts of the methyl methacrylate copolymer and 45 parts ofthe impact resistance modifier were pelletized, followed by formationinto a sheet. The sheet was evaluated in the similar manner as inExample 1 and the results are shown in Table 2.

EXAMPLE 7

As a methyl methacrylate copolymer, “ACRYLITE M-30-003” (trade name;manufactured by CYRO Industries) was used as in Example 6.

Preparation of Impact Resistance Modifier:

(a) Preparation of Rubbery Polymer

A rubbery polymer was prepared in the same manner as in Example 1.

(b) Preparation of Outer Layer

In a glass reactor were charged 60 parts (as a solid content) of thecrosslinked rubbery polymer latex obtained in (a), 0.11 part of sodiumformaldehyde sulfoxylate, 0.026 part of sodiumethylenediaminetetraacetate and 0.013 part of ferrous sulfateheptahydrate. At 50° C., the aqueous dispersion was stirred underheating in a nitrogen gas stream. Then, as monomer components for graftpolymerization, 33 parts of methyl methacrylate and 7 parts ofacrylonitrile and, as a polymerization initiator, 0.07 part of cumenehydroperoxide were added continuously over 2 hours. After completion ofthe addition, 0.17 part of cumene hydroperoxide and 0.2 part of sodiumformaldehyde sulfoxylate were added. One hour later, 0.17 part of cumenehydroperoxide and 0.2 part of sodium formaldehyde sulfoxylate wereadded. Stirring was continued for 1 hour to complete the polymerization.A monomer-to-polymer ratio was 97%. The graft copolymer latex having amultilayer structure thus obtained was then subjected to salting-out andcoagulation, heat treatment and drying in a known manner to therebyobtain a white powdery product.

Preparation of Resin Composition:

As in Example 1, a mixture obtained by adding 0.2 part of an olefinlubricant (“ACPE-629A”, manufactured by Allied Signal Inc.) and 1 partof an ultraviolet absorber (“TINUVIN-P”, manufactured by Ciba SpecialtyChemicals) to 47.5 parts of a methyl methacrylate copolymer and 52.5parts of the resulting impact resistance modifier was kneaded in atwin-screw kneader, followed by pelletization and formation of a sheet.

The sheet was evaluated in the same manner as in Example 1 and theresults are shown in Table 2.

EXAMPLE 8

As a methyl methacrylate copolymer, “ACRYLITE M-30-003” (trade name;manufactured by CYRO Industries) was used as in Example 6.

Preparation of Impact Resistance Modifier:

(a) Preparation of Rubbery Polymer

A rubbery polymer was prepared in the same manner as in Example 1.

(b) Preparation of Outer Layer

In a glass reactor were charged 40 parts (as a solid content) of thecrosslinked rubbery polymer latex obtained in (a), 0.16 part of sodiumformaldehyde sulfoxylate, 0.04 part of sodiumethylenediaminetetraacetate and 0.02 part of ferrous sulfateheptahydrate. At 50° C., the aqueous dispersion was stirred underheating in a nitrogen gas stream. Then, as monomer components for graftpolymerization, 49 parts of methyl methacrylate and 11 parts ofacrylonitrile and, as a polymerization initiator, 0.08 part of cumenehydroperoxide were added continuously over 3 hours. After completion ofthe addition, 0.17 part of cumene hydroperoxide and 0.2 part of sodiumformaldehyde sulfoxylate were added. One hour thereafter, 0.17 part ofcumene hydroperoxide and 0.2 part of sodium formaldehyde sulfoxylatewere added. Stirring was continued for 1 hour to complete thepolymerization. A monomer-to-polymer conversion ratio was 96%. The graftcopolymer latex having a multilayer structure thus obtained was thensubjected to salting-out and coagulation, heat treatment and drying in aknown manner to thereby obtain a white powdery product.

Preparation of Resin Composition:

As in Example 1, a mixture obtained by adding 0.2 part of an olefinlubricant (“ACPE-629A”, manufactured by Allied Signal Inc.) and 1 partof an ultraviolet absorber (“TINUVIN-P”, manufactured by Ciba SpecialtyChemicals) to 21.3 parts of a methyl methacrylate copolymer and 78.7parts of the resulting impact resistance modifier was kneaded in atwin-screw kneader, followed by pelletization and formation of a sheet.

The sheet was evaluated in the same manner as in Example 1 and theresults are shown in Table 2.

EXAMPLE 9

In the same manner as in Example 6 except that the composition of theouter layer of the impact resistance modifier was changed to 25 parts ofmethyl methacrylate and 5 parts of glycidyl methacrylate, pelletizationand sheet formation were carried out. The sheet thus obtained wasevaluated in the same manner as in Example 1 and the results are shownin Table 2.

COMPARATIVE EXAMPLE 2

In the same manner as in Example 6 except that the composition of theouter layer of the impact resistance modifier was changed to 25 parts ofmethyl methacrylate and 5 parts of butyl acrylate, pelletization andsheet formation were carried out. The sheet thus obtained was evaluatedin the same manner as in Example 1 and the results are shown in Table 2.

EXAMPLE 10

Preparation of Three-layer Impact Resistance Modifier:

(a) Preparation of Innermost Layer

In a glass reactor was charged a mixture having the below-describedcomposition. While stirring in a nitrogen gas stream, the mixture washeated to 80° C. In the reactor was charged 20% of a mixture, as theinnermost layer component, composed of 35 parts of methyl methacrylate,0.14 part of allyl methacrylate and 0.14 part of t-butyl hydroperoxidein one operation and polymerization was conducted for 45 minutes.

Mixture: (parts) Deionized water 220 Boric acid 0.3 Sodium carbonate0.03 Sodium N-lauroylsarcosinate 0.09 Sodium formaldehyde sulfoxylate0.09 Sodium ethylenediaminetetraacetate 0.006 Ferrous sulfateheptahydrate 0.002

Over 1 hour, 80% of the remaining portion of the mixture was then addedcontinuously. After completion of the addition, the mixture wasmaintained at the same temperature for 2 hours to complete thepolymerization. During this time, 0.2 part of sodiumN-lauroylsarcosinate was added. The polymer particles in the crosslinkedmethacrylic polymer latex serving as an innermost layer had an averageparticle size of 1600 Å (determined by making use of scattering of alight having a wavelength of 546 nm) and a monomer-to-polymer conversionratio (preparation amount of polymer/amount of monomer charged×100) was98%.

(b) Preparation of Rubbery Polymer

The crosslinked methacrylic polymer latex obtained above in (a) wasmaintained at 80° C. in a nitrogen gas stream. After addition of 0.1part of potassium persulfate, a monomer mixed solution of 52 parts ofn-butyl acrylate, 13 parts of styrene and 1 part of allyl methacrylatewas added continuously over 5 hours. During the addition, 0.1 part ofpotassium oleate was added in 3 portions. After completion of theaddition of the monomer mixed solution, 0.05 part of potassiumpersulfate was added further in order to complete the polymerization andthe mixture was maintained for 2 hours. The polymer thus obtained had anaverage particle size of 2300 Å and a monomer-to-polymer conversionratio was 99%.

(c) Preparation of Outermost Layer

After addition of 0.02 part of potassium persulfate to 75 parts of therubbery polymer latex which had been obtained above in (b) andmaintained at 80° C., a mixed solution of 20 parts of methylmethacrylate and 5 parts of acrylonitrile were added continuously over 1hour. After completion of the addition of the monomer mixed solution,0.02 part of potassium persulfate was added and the resulting mixturewas maintained for 2 hours to thereby obtain a multilayer graftcopolymer latex. The graft copolymer having a multilayer structure hadan average particle size of 2530 Å and a monomer-to-polymer conversionratio was 97%. The resulting multi-layer graft copolymer latex wassubjected to salting-out and coagulation, heat treatment and drying in aknown manner to thereby obtain a multilayer graft copolymer as whitepowder.

Preparation of Resin Composition:

The resulting impact resistance modifier (45 parts) and as a methylmethacrylate copolymer, 55 parts of ACRYLITE M-30-003″ (trade name;manufactured by CYRO Industries) were used. In a similar manner toExample 1, they were pelletized, followed by formation into a sheet. Thesheet was evaluated in the same manner as in Example 1 and the resultsare shown in Table 2.

TABLE 2 Comp. Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 2 Monomer AN AN AN GMAAN SP value (cal/cm³) 14.0 14.0 14.0 11.9 14.0 Amount used (%) 2.3 3.78.7 2.3 2.3 0 G. I. (inch · lb/mil) 0.89 1.21 4.62 1.05 1.08 0.59 AN:Acrylonitrile GMA: Glycidyl methacrylate

INDUSTRIAL APPLICABILITY

By using the acrylic resin composition of the present invention as acapstock, a siding panel excellent in weather resistance, impactresistance, surface hardness and processability and having a low grosscan be obtained.

1. An article of manufacture, comprising: a substrate; and a capstocklaminated with said substrate, said capstock being made from a resincomposition for capstock, comprising: 80 to 40 parts by weight of animpact resistance modifier having a multilayer structure, and 20 to 60parts by weight of a methyl methacrylate (co)polymer containing 50 to100% by weight of methyl methacrylate and 50 to 0% by weight of amonomer(s) which is copolymerizable therewith, wherein the total amountof the impact resistance modifier and the methyl methacrylate(co)polymer is 100 parts by weight, wherein the outer layer of saidimpact resistance modifier and/or said methyl methacrylate copolymer iscopolymerized with 0.5 to 40% by weight of reactive monomer(s) based onthe total amount of the impact resistance modifier and the methylmethacrylate (co)polymer as a polymer component, wherein said reactivemonomer is one or more monomer(s) selected from acrylonitrile,methacrylonitrile, glycidyl methacrylate, 2-hydroxyethyl acrylate,2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, acrylic acid, andmethacrylic acid, wherein the homopolymer of said reactive monomer hasan SP value of 9.8 (cal/cm³)^(1/2) or more, and wherein the impactresistance modifier has a two-layer structure and is obtained bypolymerizing a monomer mixture containing (meth)acrylic ester(s) andcopolymerizable monomer(s) in the presence of a crosslinked acrylicrubber.
 2. The article of manufacture according to claim 1, wherein theouter layer of said impact resistance modifier and/or said methylmethacrylate (co)polymer is copolymerized with 1 to 20% by weight of thereactive monomer based on the total amount of the impact resistancemodifier and the methyl methacrylate (co)polymer.
 3. The article ofmanufacture according to claim 1, wherein the SP value of thehomopolymer of the reactive monomer is 10.8 (cal/cm³)^(1/2) or more. 4.The article of manufacture according to claim 1, wherein a weight ratioof the crosslinked rubber portion and the outer layer portion of saidimpact resistance modifier is 15/85 to 95/5.
 5. The article ofmanufacture according to claim 1, wherein the substrate is a sidingpanel made of polyvinyl chloride.
 6. The article of manufactureaccording to claim 1, which is a siding panel obtained byextrusion-molding said resin composition as the capstock and a polyvinylchloride resin as the substrate.
 7. The article of manufacture accordingto claim 1, which is a siding panel obtained by extrusion-molding saidresin composition as the capstock and a polyvinyl chloride resin as thesubstrate using a multimanifold die.
 8. The article of manufactureaccording to claim 1, wherein the reactive monomer is used for eitherthe outer layer of the impact resistance modifier or the methylmethacrylate (co)polymer.
 9. The article of manufacture according toclaim 1, wherein the impact resistance modifier having a multilayerstructure is obtained by one-stage or at least two-stage polymerizationof a vinyl monomer in the presence of rubbery polymer particles.
 10. Anarticle of manufacture, comprising: a substrate; and a capstocklaminated with said substrate, said capstock being made from a resincomposition for capstock, comprising: 80 to 40 parts by weight of animpact resistance modifier having a multilayer structure, and 20 to 60parts by weight of a methyl methacrylate (co)polymer containing 50 to100% by weight of methyl methacrylate and 50 to 0% by weight ofmonomer(s) which is copolymerizable therewith, wherein the total amountof the impact resistance modifier and the methyl methacrylate(co)polymer is 100 parts by weight, wherein the outer layer of saidimpact resistance modifier and/or said methyl methacrylate copolymer iscopolymerized with 0.5 to 40% by weight of reactive monomer(s) based onthe total amount of the impact resistance modifier and the methylmethacrylate (co)polymer as a polymer component, wherein said reactivemonomer is one or more monomer(s) selected from acrylonitrile,methacrylonitrile, glycidyl methacrylate, 2-hydroxyethyl acrylate,2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, acrylic acid, andmethacrylic acid, wherein the homopolymer of said reactive monomer hasan SP value of 9.8 (cal/cm³)^(1/2) or more, and wherein the impactresistance modifier has a three-layer structure and is obtained by thesteps of: (1) obtaining a polymer by polymerizing methyl methacrylate,copolymerizable monomer(s) and crosslinking monomer(s); (2) polymerizingan alkyl acrylate, copolymerizable monomer(s) and crosslinkingmonomer(s) in the presence of the polymer of step (1) to yield a twolayer polymer; and then (3) polymerizing a monomer mixture containing(meth)acrylic ester(s) and copolymerizable monomer(s) in the presence ofthe resulting two-layer polymer of step (2), to produce the outer layerportion of the three-layer structure.
 11. The article of manufactureaccording to claim 10, wherein a weight ratio of the crosslinked rubberportion and the outer layer portion of said impact resistance modifieris 15/85 to 95/5.